The present invention relates generally to stump grinding machines of the type having a grinding wheel located at the distal end of a movable boom. More particularly, the invention relates to a stump grinding machine incorporating a novel support structure for pivotally mounting the boom to the machine's frame.
Stump grinding machines are widely used to remove tree stumps. These machines are constructed having a grinding wheel located at the distal end of a movable boom. Typically, the grinding wheel is swept back and forth in a generally horizontal plane across the tree stump. With each sweep, the grinding wheel is lowered slightly to remove more of the stump. The final sweeps of the grinding wheel may be below ground level to ensure elimination of the entire stump.
Often, stump grinding machines have a wheeled frame structure to facilitate movement of the machine from place to place. The frame may be self-propelled or configured for towing behind a separate vehicle. An engine, typically a gasoline or diesel engine, located on the wheeled frame generates power to drive the grinding wheel.
The grinding wheel generally receives power from the engine through a series of belts. In one known arrangement, a first belt connects the engine output to a rotatable idler shaft. A second belt is connected between the idler shaft and the grinding wheel. The idler shaft thus rotates at very high speeds to transmit power to the grinding wheel.
In addition to facilitating the transmittal of power from the engine to the grinding wheel, the idler shaft serves to pivotally support the machine's boom. To allow the idler shaft to rotate, the boom is mounted about the rotating idler shaft by bearings. Such an arrangement is disclosed in U.S. Pat. No. 6,003,570 entitled "Stump Grinder Machine Having Turntable Mounted Engine Arrangement," incorporated herein by reference.
Arrangements utilizing an idler shaft to transmit power to the cutting wheel have worked generally well for their intended purpose. It has been found, however, that vibrations generated at the stump grinding wheel may be transmitted to the bearings used to support the boom on the idler shaft. The combination of vibration and the rotational speed of the bearings' inner race gives rise to various maintenance considerations.